The development of a small, battery-operated instrument capable of identifying and quantifying organic vapors at low- and sub-ppm concentrations is proposed. The instrument will weigh less than one pound and will be about the size of a standard sampling pump. It will employ an array of polymer-coated surface-acoustic-wave (SAW) microsensors in conjunction with a miniature preconcentrator for vapor detection. Temperature and humidity compensation will also be incorporated. The patterns of responses obtained from the array will be used to identify specific vapors and to discriminate the components of vapor mixtures. Laboratory and field testing 'will demonstrate the capability for direct measurement of personal breathing-zone concentrations of a broad range of organic vapors and vapor mixtures. It will also be shown that with slight modification the instrument can be used to assess the barrier effectiveness of chemical protective clothing samples. It could thus serve as a simple alternative to complex, expensive analyzers in routine or emergency-response work situations involving potential contact with unknown liquid mixtures. In conjunction with the work just described, a computerized decision logic will be developed using multivariate statistics and Monte Carlo simulations, for determining the optimal set of sensor to include in the sensor array for any vapor analysis problem and for predicting the performance of the instrument in terms of the accuracy of identification and quantification. Current personal monitoring instrumentation cannot provide selective analysis of multiple organic vapors. By providing such capabilities, the proposed instrument will improve the quantity and quality of personal exposure data needed for characterizing the distributions of organic-vapor exposures received by workers and determining compliance with accepted exposure limits. It will also facilitate efforts by employers to meet OSHA-mandated requirements for documenting the barrier effectiveness of protective clothing used to prevent contact dermatoses and systemic effects arising from dermal absorption of toxic chemicals.